1. Field of the Invention
The present invention relates to a compact, lamination status inspecting apparatus, a lamination status inspecting method, and a lamination status detecting program for inspecting a lamination status of adjacent sheets.
2. Description of the Related Art
In recent years, a material called prepreg is widely used in fields of aerospace and sports, in which materials are required to be light-weight and of high performance. Prepreg is a sheet-like, in-process, molding material in a semi-cured state manufactured by impregnating a carbon fiber with a thermosetting resin. Plural prepreg sheets are united together to form a multilayer laminate which is then molded through thermal hardening.
If a prepreg sheet overlaps with an adjacent prepreg sheet during a lamination process, or a gap between adjacent prepreg sheets is wide, strength of a finished molded product could be insufficient. Therefore, in the lamination process, it is necessary to check an overlap of the adjacent sheets and an amount of gap therebetween so as to inspect if the sheets are properly adhered with each other.
To detect an overlap of adjacent sheets and to measure a gap amount, a level difference between the sheets needs to be detected. As a technique for detecting a level difference, an apparatus is disclosed in Japanese Patent Application Laid-open No. 2001-183113. The disclosed apparatus forms a shade of a step using two illuminations, receives reflected lights of the illuminations respectively by two sensors utilizing characteristic of reflection and transmission of a mirror thereby obtaining two images, and detects a level difference in inspected objects based on a difference between the two images.
Conventionally, whether adjacent sheets are properly adhered with each other is manually inspected. However, this procedure has a problem in that a person cannot thoroughly inspect the sheets because of their significantly large lamination areas and that the check requires high manpower cost and time.
Further, the apparatus of Japanese Patent Application Laid-open No. 2001-183113 has problems in that the apparatus has a large size because of a mirror, two light-receiving sensors, and lenses, and that high precision is required in positioning of the two light-receiving sensors because of the use of a difference.